Python Data Science Essentials - Third Edition

Regression

In tasks where you have to predict real numbers or regression, many error measures are derived from Euclidean algebra:

• Mean absolute error or MAE: This is the mean L1 norm of the difference vector between the predicted and real values:

In: from sklearn.metrics import mean_absolute_error     mean_absolute_error([1.0, 0.0, 0.0], [0.0, 0.0, -1.0])   Out: 0.66666666666666663

• Mean squared error or MSE: This is the mean L2 norm of the difference vector between the predicted and real values:

In: from sklearn.metrics import mean_squared_error     mean_squared_error([-10.0, 0.0, 0.0], [0.0, 0.0, 0.0])Out: 33.333333333333

• R² score: R² is also known as the coefficient of determination. In a nutshell, R² determines how good a linear fit there ...